A dashboard can show the results of Nightly and Continuous builds of a software package. This includes warnings and errors from the configure and build process as well as the results of the executed tests belonging to the software package. This is not only displayed for one machine, but ideally for all supported operating systems such results are submitted, also with different configurations, e.g. one for a minimal system with most optional features disabled and one for a full featured system.
For KDE CDash-based dashboards are set up at http://my.cdash.org, a service provided by Kitware. CDash only displays the results, the actual building and testing is done decentral on other machines. When failures occur, like build errors or failed tests, notification emails can be sent by CDash. So by building and testing KDE each day on the supported platforms and collecting the results in a central place, we can make sure that KDE stays compiling and also working on all supported platforms.
You can help too to increase the quality by setting up a Nightly build and submitting the results to http://my.cdash.org.
Currently there are dashboards set up for all modules of KDE, and one for kdesupport. There are not yet dashboards for extragear and koffice. If you are interested in setting dashboards up for these too, just go to http://my.cdash.org and do it, or ask on the kde-buildsystem mailing list if you have any questions.
So, here comes the list of currently existing KDE dashboards: